The method as outlined above is commonly used for cleaning kaolien and metal ore. The filter element of such a separator is, e.g., steelwool which is subjected to a magnetic field of high intensity; the difference in magnetic properties results in that, dependent upon the field strength, the velocity and viscosity of the fluid and of the temperature certain particles are caught in the steelwool, and others are not.
This method is e.g. described in IEEE Transactions on Magnetics, Vd. Mag-12, no. 5, September 1976 and in the U.S. Pat. Nos. 3,887,457 and 3,988,240.
It is known in itself that of many paramagnetic particles the magnetic susceptibility (X=M/H) is temperature-dependent, and inversally proportional to the absolute temperature (.degree.K.). It is to be expected that the method as described above will be more effective at lower temperatures than at higher temperatures, but until now the separation method is not carried out at low temperatures because cooling the separator to a sufficient low temperature is very costly and requires a complex and costly structure.